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2. Biology: What is Life? life study of Properties of Life
Cellular Structure: the unit of life, one or many
Metabolism: photosynthesis, respiration, fermentation, digestion, gas exchange, secretion, excretion, circulation--processing materials and energy
Growth: cell enlargement, cell number
Movement: intracellular, movement, locomotion
Reproduction: avoid extinction at death
Behavior: short term response to stimuli
Evolution: long term adaptation

3. Organismal Circulation
Unicellular Organisms
Autotrophic Multicellular Organisms
(Heterotrophic Multicellular Organisms)

4. Cyclosis in Physarum polycephalum, a slime mold
This organism consists of one very large cytoplasm (plasmodium) with many nuclei and food vacuoles in the cytosol (coenocytic).
Slime molds can weigh up toward kilogram range and move their blob-like mass around exclusively by cyclosis.
Here you can see, in a thin region of cytoplasm, that it moves along pathways that are river-like in appearance.
Transport is NOT always unidirectional.
The correct taxonomic affiliation is unclear.
It has been treated as Fungus and Protist.
Further study is needed to resolve its position.
What is the ATP source?

5. Cyclosis: cytoplasmic streaming…intracellular circulation
Elodea canadensis
Chloroplasts and other organelles have surface proteins with myosin-like activity.
Microfilaments of actin are found just under cell membrane.
ATP and Calcium allow myosin to slide along actin filaments, resulting in circulation of organelles within the cell.
What is the source of ATP?
Can you be more specific?
If light intensity were reduced, what would be the prediction based on your hypothesis?

6. Figure 36-3 Page 793
Apical bud
The shoot organ system is photoautotrophic, taking in CO2 and releasing O2 in daylight.
Axillary bud
Node
CO2 in and O2 out
Internode
Node
Shoot system
Leaves
Branch
O2 in and CO2 out
Diffusion is sufficient to exchange gases. But solutes need to be circulated in the large plant body as diffusion is too slow!!
Stem
Lateral roots
The root organ system is chemoheterotrophic, taking in O2 and releasing CO2 in the darkness of the soil environment.
Root system
O2 in and CO2 out
Taproot

7. Carbohydrate etc. Transpiration Translocation Water and Minerals
Figure 36-3 Page 793
Apical bud
The shoot system produces carbohydrates (etc.) by photosynthesis. These solutes are transported to the roots in the phloem tissue:
Translocation
Axillary bud
Node
Carbohydrate etc.
Internode
Node
Shoot system
Leaves
Branch
Stem
Transpiration
Translocation
The root system removes water and minerals from the soil environment. These solutes are transported to the shoot in the xylem tissue:
Transpiration
Lateral roots
Root system
Water and Minerals
Taproot

8. Carbohydrate etc. Transpiration Translocation Water and Minerals
Figure 36-3 Page 793
Apical bud
Axillary bud
Node
Carbohydrate etc.
Internode
Because these pathways involve solutes in water passing in the adjacent tissues of a narrow vascular bundle, this is a circulation system!
Transpiration and Translocation
The water is moving up the xylem, and down the phloem, making a full circuit!
Node
Shoot system
Leaves
Branch
Stem
Transpiration
Translocation
Lateral roots
Root system
Water and Minerals
Taproot

9. Plants occur in two major groups (and some minor ones)
Figure Page 802
Plants occur in two major groups (and some minor ones)
They differ, in part, in their circulation systems:
Cross section of a eudicot stem
Cross section of a monocot stem
Epidermis
Cortex
Ground tissue
Pith
Vascular bundles
Dicots initially have one ring of vascular bundles
Monocots rapidly develop multiple, concentric, rings of vascular bundles

10. Monocot circulation: transpiration and translocation
©1996 Norton Presentation Maker, W. W. Norton & Company

11. Monocot stem anatomy Mature Monocot Young Monocot vascular bundles
As a monocot plant grows in diameter, new bundles are added toward the outside for increased circulation to the larger plant body.

12. Is this slice from a young or a mature part of the corn stem?
Monocot stem anatomy
Let’s take a closer look at the vascular tissues
©1996 Norton Presentation Maker, W. W. Norton & Company

13. Why must xylem do a lot more transport than phloem?
Monocot stem anatomy: vascular bundle
Translocation
Transpiration
©1996 Norton Presentation Maker, W. W. Norton & Company
Why must xylem do a lot more transport than phloem?

14. Dicot circulation: stem anatomy Dicots start with one ring of bundles…
Let’s take a closer look at the vascular tissues
©1996 Norton Presentation Maker, W. W. Norton & Company

15. Cell Divison: More Xylem and Phloem
Dicot stem anatomy: vascular bundle
phloem fibers
Support of Stem
functional phloem
Translocation
vascular cambium
Cell Divison: More Xylem and Phloem
xylem
Transpiration
As a dicot grows, how does it add vascular capacity to become a tree?
©1996 Norton Presentation Maker, W. W. Norton & Company

16. Dicot stem anatomy: vascular cambium adds secondary tissues
epidermis
cortex
1º phloem
2º phloem
cambium
2º xylem
1º xylem
pith

17. Dicot stem anatomy: vascular cambium adds secondary tissues
©1996 Norton Presentation Maker, W. W. Norton & Company
Each year the vascular cambium make a new layer of secondary xylem and secondary phloem

18. Dicot stem anatomy: four year-old stem (3 annual growth rings)
phloem etc. = bark
All of these tissues were added by the vascular cambium!
xylem = wood
©1996 Norton Presentation Maker, W. W. Norton & Company

19. cambium phloem or less competition in forest?
Figure Page 810 See also part (a)
or less competition in forest?
or more competition in forest?
cambium
phloem

20. sapwood heartwood pith periderm phloem cambium = bark
Figure 36.0 Page 791
periderm phloem cambium = bark
sapwood
heartwood
pith

21. Dicot stem anatomy: 2-year old stem showing ray and periderm
©1996 Norton Presentation Maker, W. W. Norton & Company

22. Dicot stem anatomy: periderm
dying epidermis
maturing cork cells
periderm
cork cambium
phelloderm
cortical collenchyma
cortical parenchyma
©1996 Norton Presentation Maker, W. W. Norton & Company

23. Two Xylem Conducting Cells: tracheid developmental sequence
Annular Helical Pitted
When flowering plants are young, water needs are limited, tracheids suffice.
The walls are strengthened with secondary thickenings including lignin.
Protoxylem have stretchable annular or helical thickenings.
Metaxylem have reticulate or pitted and fully rigid walls.
Tracheids have end walls and flow between cells is through pits.
©1996 Norton Presentation Maker, W. W. Norton & Company

24. Dicot stem anatomy: xylem vessel evolution plesiomorphic apomorphic
As flowering plants age and grow, water needs increase, and tracheids need to be supplemented.
Flowering plants evolved xylem cells with larger cell diameter and perforated end walls to increase water flow.
Vessels have perforated end walls or lack end walls, but lateral flow between cells is still through pits.
©1996 Norton Presentation Maker, W. W. Norton & Company

25. Dicot stem anatomy: xylem parenchyma, vessels, and tracheids
©1996 Norton Presentation Maker, W. W. Norton & Company

26. Dicot stem anatomy: xylem parenchyma, vessels, and tracheids
©1996 Norton Presentation Maker, W. W. Norton & Company
The huge vessel transports lots of water longitudinally, and shows lots of pits for lateral transport

27. Dicot stem anatomy: woody stem circulation
This sketch is showing the importance of lateral transport.
In both transpiration and translocation materials must move radially to the interior and to the exterior as well as up and down the plant.
O2 in and CO2 out
©1996 Norton Presentation Maker, W. W. Norton & Company

28. Secondary xylem: cross sections of three species
©1996 Norton Presentation Maker, W. W. Norton & Company
Vessels, Tracheids have different distribution patterns.
Some produce big vessels only in spring wood
Others produce vessels year-round.

29. Xylem and Phloem: tissues with many cell types but conduction function
©1996 Norton Presentation Maker, W. W. Norton & Company

30. Mendocino Tree (Coastal Redwood) Sequoia sempervirens
Ukiah, California
112 m tall (367.5 feet)!
This tree is more than ten times taller than is “theoretically possible” based solely upon the length of the column of uncavitated water.
How could this be achieved?

31. Transpiration in a tall tree has at least 3 critical components:
Evaporation: pulling up water from above
Capillarity: climbing up of water within xylem
Root Pressure: pushing up water from below

32. Transpiration: root pressure (osmotic “push”)
Solutes from translocation of sugars accumulate in roots.
Water from the soil moves in by osmosis.
Accumulating water in the root rises in the xylem.
Water escapes from hydathodes.
guttation
©1996 Norton Presentation Maker, W. W. Norton & Company
This is not “dew” condensing!

33. Transpiration: root pressure (osmotic “push”)
The veins (coarse and fine) show that no cell in a leaf is far from xylem and phloem (i.e.water and food!).
The xylem of the veins leaks at the leaf margin in a modified stoma called the hydathode.
These droplets are xylem sap.
Root pressure accounts for maybe a half-meter of “push” up a tree trunk.

34. Capillarity: maximum height of unbroken water column
glass tube
vacuum created
The small diameter of vessels and tracheids and the surface tension of water provide capillary (“climb”).
Cohesion of water, caused by hydrogen bonds, helps avoid cavitation.
A tree taller than 10.4 m would need some adaptations to avoid “cavitation”
gravity pulls water down
10.4m
atmospheric pressure keeps water in tube
water

35. Dicot stem anatomy: pine xylem tracheids with pits, xylem rays
vascular cambium
vascular cambium
tracheids with pits
In spite of the limitations of tracheids-only xylem, conifers are among the tallest of trees!
ray parenchyma
©1996 Norton Presentation Maker, W. W. Norton & Company

36. Conifer stem anatomy: bordered pits as “check-valve” for flow
secondary wall
primary wall
middle lamella
pit aperture
pit membrane
These pit features allow conifers to be very tall and still avoid cavitation in their xylem cells.
As pressures change between adjacent cells, the torus movement blocks catastrophic flow that would result in cavitation.
pit border
torus
pit chamber
P low
P high

37. Transpiration: evaporation (“pull”)
Transpiration can lift the mercury above its normal cavitation height!
vacuum
water
mercury
Water evaporating from a porous clay cap also lifts the mercury!
76 cm
mercury

38. Grown in 32PO4 (radioactive phosphorus) 1 hour
“Cold” medium 6 hours
“Cold” medium 90 hours
new growth black
©1996 Norton Presentation Maker, W. W. Norton & Company
note: fading
Is phosphate mobilization from lower leaf:
transpiration or translocation?
In xylem or phloem?
Is phosphate uptake from soil:
transpiration or translocation?
In xylem or phloem?

39. Translocation: How solutes move in phloem
Leaf
High Pressure
plasmodesmata
Root
active transport
Low Pressure
Modified from: ©1996 Norton Presentation Maker, W. W. Norton & Company

40. Translocation: How solutes move bidirectionally in phloem
Low Pressure
Developing leaves, apical bud, flowers fruits
Leaf sugars amino acids
High Pressure
Lateral buds, stems, roots, root tip
Low Pressure
Modified from: ©1996 Norton Presentation Maker, W. W. Norton & Company

41. Transpiration Carbohydrate etc. Transpiration Translocation
Apical bud
Axillary bud
Node
Evaporation:
Water evaporates from mesophyll into atmosphere.
Water molecules are pulled up the xylem by virtue of cohesion.
Carbohydrate etc.
Internode
Node
Shoot system
Leaves
Branch
Capillarity:
Water climbs in the xylem cell walls by adhesion.
Water molecules follow by cohesion.
Stem
Transpiration
Translocation
Lateral roots
Root Pressure:
Water moves into the root because of solutes from phloem.
Pressure pushes the water up the stem.
Root system
Water and Minerals
Taproot
Figure 36-3 Page 793

42. Translocation Carbohydrate etc. Transpiration Translocation
Apical bud
Axillary bud
Node
Leaf = Source
Photosynthesis produces solutes.
Solutes loaded into phloem by active transport.
Water follows by osmosis, increasing pressure.
Carbohydrate etc.
Internode
Node
Shoot system
Leaves
Branch
Stem
Transpiration
Translocation
Root (etc.) = Sinks
Solutes removed from phloem by active transport.
Water follows by osmosis, reducing pressure.
Lateral roots
Root system
Pressure = Bulk Flow
The pressure gradient forces phloem sap away from leaves to all sinks (bidirectionally).
Water and Minerals
Taproot
Figure 36-3 Page 793